Little bit of poetry mother's penning (7)
I believe the answer is:
modicum
'little bit' is the definition.
(modicum means a very small amount)
'poetry mother's penning' is the wordplay.
'poetry' becomes 'odic' (I've seen this in other clues).
'mother' becomes 'mum' (informal term for mother).
'penning' is an insertion indicator.
'odic' inserted inside 'mum' is 'MODICUM'.
'of' acts as a link.
(Other definitions for modicum that I've seen before include "Tad" , "A small amount as of drink" , "A small portion" , "suggestion" , "Moderate quantity" .)