Time lost in expensive leak (4)
I believe the answer is:
seep
'leak' is the definition.
(thesaurus)
'time lost in expensive' is the wordplay.
'time' becomes 't'.
'lost in' indicates named letters should be taken away.
'expensive' becomes 'steep' (I've seen this before).
'steep' with 't' removed is 'SEEP'.
(Other definitions for seep that I've seen before include "Leak gradually" , "Of liquid, ooze slowly out" , "Leak slowly, ooze" , "Leak through an opening" , "Ooze, percolate" .)