Is this what prompts wool gathering? (4,8)
I believe the answer is:
herd instinct
'is this what prompts wool' is the definition.
The definition suggests a singular noun which matches the answer.
'gathering?' is the wordplay.
I cannot quite see how this works, but
'gathering?' could be 'herd' (herd is a kind of gathering) and 'herd' is located in the answer.
The remaining letters 'instinct' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for herd instinct that I've seen before include "Safety-in-numbers feeling" , "Animals' natural togetherness" , "new feeling of congregation" .)