Substitute having lifted silver trophy’s heading for pub (7)
I believe the answer is:
stopgap
'substitute' is the definition.
(I've seen this before)
'lifted silver trophy's heading for pub' is the wordplay.
'lifted' is a reversal indicator (going up in down clue).
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'trophy's' becomes 'pot's'.
'heading for' suggests taking the first letters.
The first letter of 'pub' is 'p'.
'ag'+'pots'='agpots'
'agpots' back-to-front is 'stopga'.
'stopga'+'p'='STOPGAP'
'having' is the link.
(Other definitions for stopgap that I've seen before include "Makeshift" , "Temporary measure" , "Interim" , "Temporary fix" , "Temporary expedient" .)