Work it loose in little opening (7)
I believe the answer is:
ostiole
'opening' is the definition.
(I've seen this before)
'work it loose in little' is the wordplay.
'work' is an anagram indicator.
'it' becomes ''t' (abbreviation. e.g. in 'tis).
'little' means to remove the last letter (the word is not quite complete).
't'+'loose'+'in'='tloosein'
'tloosein' with its last letter removed is 'tloosei'.
'tloosei' with letters rearranged gives 'OSTIOLE'.
(Other definitions for ostiole that I've seen before include "opening" , "Hole" .)