Mad about braid (5)
I believe the answer is:
rabid
'mad' is the definition.
(I've seen this before)
'about braid' is the wordplay.
'about' is an anagram indicator.
'braid' is an anagram of 'RABID'.
(Other definitions for rabid that I've seen before include "Mad; raging" , "Zealous" , "Affected by hydrophobia" , "Fanatical - hydrophobic" , "extremist" .)