Having come down, it's on the left (3)
I believe the answer is:
lit
'having come down' is the definition.
I can't tell whether this defines the answer.
'it's on the left' is the wordplay.
'it's' becomes 'it' (I've seen this in other clues).
'on' says to put letters next to each other.
'the left' becomes 'l' (common abbreviation).
'it' after 'l' is 'LIT'.
Can you help me to learn more?
(Other definitions for lit that I've seen before include "Settled" , "fine writing in condensed form" , "Set afire" , "Burning" , "Creative writing, in short" .)