Sort of bread regularly seen in rhyme (3)
I believe the answer is:
rye
'sort of bread' is the definition.
'regularly seen in rhyme' is the wordplay.
'regularly seen in' indicates alternate letters.
The alternating letters of 'rhyme' are 'RYE'.
(Other definitions for rye that I've seen before include "J D Salinger novel 'The Catcher in the ...'" , "Grass; whisky" , "Gypsy gentleman" , "Whisky; Sussex town" , "Cereal - liquor" .)