Cricket side on green, perhaps, having a minor complaint? (3-6)
I believe the answer is:
'having a minor complaint?' is the definition.
(with a minor medical complaint)
'cricket side on green' is the wordplay.
'cricket side' becomes 'off'.
'on' says to put letters next to each other.
'green' becomes 'colour' (green is a colour).
'perhaps' acts as a link.
(Other definitions for off-colour that I've seen before include "Ailing - blue" , "Unwell, lacking pigment?" , "Not in the pink?" , "Unwell -- risque" , "Rather poorly" .)