Put back an inverted spike (7)
I believe the answer is:
replace
'put back' is the definition.
(I know that put back can be written as replace)
'an inverted spike' is the wordplay.
'an' becomes 'per' (synonymous as in 'once an hour', 'once per hour').
'inverted' is a reversal indicator.
'spike' becomes 'lace' (synonyms).
'per' backwards is 'rep'.
'rep'+'lace'='REPLACE'
(Other definitions for replace that I've seen before include "Put back in original position" , "Substitute, supersede" , "Substitute for (someone)" , "succeed" , "Substitute, supplant" .)