Answer concerning small garden feature (7)
I believe the answer is:
respond
'answer' is the definition.
(I know that answer can be written as respond)
'concerning small garden feature' is the wordplay.
'concerning' becomes 're' (both can mean on a particular topic).
'small' becomes 's' (abbreviation - e.g. clothes size).
'garden feature' becomes 'pond' (I've seen this in another clue).
're'+'s'+'pond'='RESPOND'
(Other definitions for respond that I've seen before include "React (positively) to a stimulus or treatment" , "Write back" , "Answer or react" , "Come back" , "Answer back" .)