Fundamentalist spoke about clubs (7)
I believe the answer is:
radical
'fundamentalist' is the definition.
(someone with radical or fundamental views)
'spoke about clubs' is the wordplay.
'spoke' becomes 'radial' (I've seen this before).
'about' means one lot of letters goes inside another.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'radial' going around 'c' is 'RADICAL'.
(Other definitions for radical that I've seen before include "Dial car in order to be drastic" , "Going to the roots, fundamental as change may be" , "objections to current policy?" , "Going to the root" , "Holding extreme political views" .)