Aggressive promotion resulting from confusion of shared lines (4,4)
I believe the answer is:
hard sell
'aggressive promotion' is the definition.
(I've seen this before)
'confusion of shared lines' is the wordplay.
'confusion of' indicates an anagram (I've seen this in other clues).
'lines' becomes 'll' (I've seen this in other clues).
'shared' with letters rearranged gives 'hardse'.
'hardse'+'ll'='HARD SELL'
'resulting from' is the link.
(Other definitions for hard sell that I've seen before include "Serious persuasion" , "Aggressive trading or advertising" , "aggressive policy?" , "remorseless flogging" , "serious flogging" .)