Frame’s hard and complete but not fine (4)
I believe the answer is:
hull
'frame's' is the definition.
(I have seen 'Frame of boat' mean 'hull' so perhaps 'frame' could also mean 'hull')
'hard and complete but not fine' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'and' says to put letters next to each other.
'complete' becomes 'full' (synonyms).
'but not' is a deletion indicator.
'fine' becomes 'f' (abbreviation in pencil classifications).
'full' with 'f' taken out is 'ull'.
'h'+'ull'='HULL'
(Other definitions for hull that I've seen before include "Frame of boat" , "Main body of ship" , "Outer covering of a seed or nut" , "Framework of ship" , "Shell of boat" .)