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' says the letters should be written in reverse (to recall can mean to bring something back).
'having' says to put letters next to each other.
'lag' back-to-front 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" .)