Search bank becoming poorer (8)
I believe the answer is:
scantier
'poorer' is the definition.
'search bank' is the wordplay.
'search' becomes 'scan'.
'bank' becomes 'tier' (I've seen this before).
'scan'+'tier'='SCANTIER'
'becoming' acts as a link.
(Other definitions for scantier that I've seen before include "more parsimonious" , "more revealing" , "less lavish" , "More frugal" .)