Convict recalled having a field day? (4)
I believe the answer is:
gala
'field day?' is the definition.
(I've seen this before)
'convict recalled having a' is the wordplay.
'convict' becomes 'lag' (slang term for a prisoner).
'recalled' shows that the letters should be reversed in order (to recall can mean to bring something back).
'having' means one lot of letters go next to another.
'lag' in reverse letter order is 'gal'.
'gal'+'a'='GALA'
(Other definitions for gala that I've seen before include "Jamboree" , "Prod with the elbow" , "Special performance" , "Festive celebration" , "Social occasion with special performances" .)