Watering plants always in season (8)
I believe the answer is:
spraying
'watering plants' is the definition.
'spraying' can be an answer for 'watering' (thesaurus). I am unsure of the 'plants' bit.
'always in season' is the wordplay.
'always' becomes 'ay' (archaic term for 'always').
'in' is an insertion indicator.
'season' becomes 'spring' (spring is a season).
'ay' placed within 'spring' is 'SPRAYING'.
Can you help me to learn more?
(Another definition for spraying that I've seen is " Dispersing insecticide on crops, say".)