Maybe roofer eating dates is not a great catch! (7)
I believe the answer is:
tiddler
'not a great catch' is the definition.
(a small fish)
'maybe roofer eating dates' is the wordplay.
'maybe roofer' becomes 'tiler' (a tiler might work on a roof).
'eating' is an insertion indicator.
'dates' becomes 'dd' (two abbreviations for date).
'tiler' enclosing 'dd' is 'TIDDLER'.
'is' acts as a link.
(Other definitions for tiddler that I've seen before include "Small thing" , "Small fish (or child?)" , "Tiny fish, child" , "Small fish (colloq,)" , "One small" .)