Monitor church paintings (5)
I believe the answer is:
chart
'monitor' is the definition.
(to chart something is to track or monitor it)
'church paintings' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'paintings' becomes 'art' (painting is a type of artwork).
'ch'+'art'='CHART'
(Other definitions for chart that I've seen before include "Marine map" , "Visual display of information" , "Nautical map" , "series of plots?" , "[LOVE ME DO] became the first of many to ..." .)