Stick a penny on this spot (6)
I believe the answer is:
adhere
'stick' is the definition.
(to adhere to something is to stick to it)
'a penny on this spot' is the wordplay.
'penny' becomes 'd' (abbreviation e.g. Lsd - pounds, shillings, pence).
'on this spot' becomes 'here' (I've seen this before).
'a'+'d'+'here'='ADHERE'
(Other definitions for adhere that I've seen before include "Stick like a stamp" , "Stick firmly" , "Header (anag)" , "Stick to as by suction" , "Stick or cleave to" .)