Insect featuring in design, a termite (4)
I believe the answer is:
gnat
'insect' is the definition.
(gnat is a kind of insect)
'in design a termite' is the wordplay.
'in' indicates a hidden word.
'GNAT' can be found hidden inside 'design a termite'.
'featuring' acts as a link.
(Other definitions for gnat that I've seen before include "Two-winged fly" , "Tiny biting insect" , "Something that bites" , "Small biting flying insect" , "insect's" .)