Nothing like this one young lady, back from institute in Donegal, having lark at The Centre (10)
I believe the answer is:
dissimilar
'this one young lady back from institute in donegal having lark at the centre' is the definition.
Both the definition and answer are adjectives. Perhaps you can see a link between them that I can't see?
'nothing like' is the wordplay.
'nothing' becomes 'dis' (I am not sure about this - if you are sure you should believe this answer much more).
'like' becomes 'similar' (synonyms).
'dis'+'similar'='DISSIMILAR'
Can you help me to learn more?
(Other definitions for dissimilar that I've seen before include "Unalike" , "Unlike" , "Not like" .)