A bit of poetry treasured by mother (7)
I believe the answer is:
modicum
'a bit' is the definition.
(thesaurus)
'poetry treasured by mother' is the wordplay.
'poetry' becomes 'odic' (I've seen this in other clues).
'treasured by' is an insertion indicator.
'mother' becomes 'mum' (mum is a kind of mother).
'odic' going inside 'mum' is 'MODICUM'.
'of' acts as a link.
(Other definitions for modicum that I've seen before include "suggestion" , "Tad" , "A small portion" , "I cod Mum into providing a small quantity" , "Mum, I cod about a small amount" .)