Live close to contaminated water supply (5)
I believe the answer is:
dwell
'live' is the definition.
(synonyms)
'close to contaminated water supply' is the wordplay.
'close to' says to take the final letters (the close/ending of).
'water supply' becomes 'well' (a well is a source of water).
The final letter of 'contaminated' is 'd'.
'd'+'well'='DWELL'
(Other definitions for dwell that I've seen before include "Reside - linger" , "Remain" , "Think moodily (on something)" , "Harp" , "Abide, reside" .)