Gear extremely religious European always wears (7)
I believe the answer is:
reverse
'gear' is the definition.
(I know that reverse is a type of gear)
'extremely religious european always wears' is the wordplay.
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'european' becomes 'E' (abbreviation e.g. EU).
'always' becomes 'ever' (synonyms).
'wears' is an insertion indicator.
'religious' with its middle removed is 'rs'.
'rs'+'e'='rse'
'rse' placed around 'ever' is 'REVERSE'.
(Other definitions for reverse that I've seen before include "Defeat - setback - other side" , "Drive backwards" , "Back (of a coin or medal)" , "Tails (of a coin)" , "Do u-turn to reserve" .)