Purchase not considered large I use my pub to exchange (7,3)

I believe the answer is:

impulse buy

'purchase not considered' is the definition.

'large i use my pub to exchange' is the wordplay.
'large' becomes 'l'.
'to exchange' is an anagram indicator.
'l'+'i'+'use'+'my'+'pub'='liusemypub'
'liusemypub' with letters rearranged gives 'IMPULSE-BUY'.

I've seen this clue in The Times.

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