Supply wren with suet feeder (3,5)
I believe the answer is:
wet nurse
'feeder' is the definition.
(I've seen this before)
'supply wren with suet' is the wordplay.
'supply' is an anagram indicator (in a supple way).
'with' says to put letters next to each other.
'wren'+'suet'='wrensuet'
'wrensuet' anagrammed gives 'WET-NURSE'.
(Other definitions for wet nurse that I've seen before include "Woman to help mum" , "Milk supplier" , "feeder" , "Coddle" , "Woman employed to suckle" .)