Coppers holding alien on resistance front (8)
I believe the answer is:
pretence
'front' is the definition.
(thesaurus)
'coppers holding alien on resistance' is the wordplay.
'coppers' becomes 'pence' (I've seen this before).
'holding' means one lot of letters goes inside another.
'alien' becomes 'et' (extra terrestrial**).
'on' means one lot of letters go next to another.
'resistance' becomes 'r' (abbreviation).
'et' put after 'r' is 'ret'.
'pence' going around 'ret' is 'PRETENCE'.
(Other definitions for pretence that I've seen before include "Invention" , "Affectation" , "Make-believe, or false claim to merit" , "Erect pen (anag) - charade" , "Deceit, dissimulation" .)