Polish worker's increase (7)
I believe the answer is:
beeswax
'polish' is the definition.
(I've seen this before)
'worker's increase' is the wordplay.
'worker's' becomes 'bee's' (a worker bee).
'increase' becomes 'wax' (waxing is a kind of increasing).
'bees'+'wax'='BEESWAX'
(Other definitions for beeswax that I've seen before include "Natural product used in polishes" , "Furniture polish" , "Hive-made polish" , "It's used to make honeycombs and candles" , "Honeycomb material" .)