Solution: Identification
Answer: BIRD TOURS

Written by Janice Heng

The easiest first step is to identify the 18 images. They are given in alpha order, which helps to disambiguate:

Given that there are 18 images and 9 clues, and the flavourtext suggests putting things together, the next step is to combine pairs of images. The required aha is realising that image pairs can form the names of birds. (For those unfamiliar with birds, the proximity of SAP and SUCKER could allow one to notice SAPSUCKER; another way in is seeing the possibility of HORNBILL.)

You might get to the next step via the popularised-by-Looney-Tunes insult “yellow-bellied sapsucker”, or simply clicking around Wikipedia: the clues correspond to the common names of specific species of these birds.

The flavourtext says “common and otherwise” -- we need both common and scientific names. This is also indicated by the use of italics and initial capitalisation, in line with binomial nomenclature formatting convention. Index into the second part to extract letters in order, for the final answer BIRD TOURS.

Clue Common name prefix Bird Scientific name Extracted letter
Having unassuming pockets Plain-pouched HORNBILL Rhyticeros subruficollis B
Cowardly Yellow-bellied SAPSUCKER Sphyrapicus varius I
Stalked by an ancient Greek string instrument? Lyre-tailed NIGHTJAR Uropsalis lyra R
Seen naked? Buff-spotted FLAMEBACK Chrysocolaptes lucidus D
Get-together after a long time Reunion STONECHAT Saxicola tectes T
Fresh twenty-one shillings New Guinea LOGRUNNER Orthonyx novaeguineae O
Grieving Mourning WHEATEAR Oenanthe lugens U
Tending to shift Variable OYSTERCATCHER Haematopus unicolor R
Pale of face White-cheeked NUTHATCH Sitta leucopsis S
Author's notes

I’m a birdwatcher, and had wanted to write a puzzle around names such as OYSTERCATCHER and SHEARWATER (not used here, in the end) for a while. The use of common names was inspired by those Twitter threads about how some bird names sound like insults.