Thirsty doctor at the eye centre (3)
I believe the answer is:
dry
'thirsty' is the definition.
(similar in meaning)
'doctor at the eye centre' is the wordplay.
'doctor' becomes 'dr' (abbreviation).
'at' says to put letters next to each other.
'centre' indicates the central letters.
The central letter of 'eye' is 'y'.
'dr'+'y'='DRY'
(Other definitions for dry that I've seen before include "Having given up drinking" , "Arid; teetotal" , "Desiccated" , "Decay in timber" , "Fine" .)