Combine egg, did you say? (4)
I believe the answer is:
knit
'combine' is the definition.
(thesaurus)
'egg did you say?' is the wordplay.
'egg' becomes 'nit' (a nit is an insect egg).
'did you say?' indicates a 'sounds like' (homophone) clue.
'nit' sounds like 'KNIT'.
(Other definitions for knit that I've seen before include "needlework?" , "Bind together" , "Make a scarf, say" , "Form by looping and entwining wool etc" , "Tighten (eyebrows) in a frown; unite" .)