Consider putting it in firm entrance (8)
I believe the answer is:
cogitate
'consider' is the definition.
(I've seen this before)
'it in firm entrance' is the wordplay.
'in' means one lot of letters goes inside another.
'firm' becomes 'co' (a firm is a company).
'entrance' becomes 'gate' (type of entrance).
'co'+'gate'='cogate'
'it' put into 'cogate' is 'COGITATE'.
'putting' acts as a link.
(Other definitions for cogitate that I've seen before include "Reflect, ponder" , "Meditate - reflect" , "Think deeply, ponder" , "Consider" , "Use little grey cells" .)