Ashen in Swansea (3)
I believe the answer is:
wan
'ashen' is the definition.
(very pale)
'in swansea' is the wordplay.
'in' says the answer is hidden in the clue.
'WAN' can be found hidden inside 'swansea'.
(Other definitions for wan that I've seen before include "Pale, looking exhausted" , "Pale and ill-looking" , "Direly pale" , "Pale; weak" , "Pale from sickness" .)