Colourless in Swansea (3)
I believe the answer is:
wan
'colourless' is the definition.
(similar in meaning)
'in swansea' is the wordplay.
'in' indicates a hidden word.
'WAN' can be found hidden inside 'swansea'.
(Other definitions for wan that I've seen before include "Pale from sickness" , "Direly pale" , "Pale as from illness" , "Pale and weak-looking" , "Faint" .)