Dried fruit that’s popular, they say (7)
I believe the answer is:
currant
'dried fruit' is the definition.
(currant is a kind of dried fruit)
'popular they say' is the wordplay.
'popular' becomes 'current' (I've seen this before).
'they say' indicates a 'sounds like' (homophone) clue.
'current' sounds like 'CURRANT'.
'that's' acts as a link.
(Other definitions for currant that I've seen before include "Dried seedless raisin" , "Small dried fruit" , "Small dried seedless grape" , "Cake ingredient" , "Small black raisin" .)