Rough, beginning to get wet (6)
I believe the answer is:
grainy
'rough' is the definition.
(thesaurus)
'beginning to get wet' is the wordplay.
'beginning to' suggests taking the first letters.
'wet' becomes 'rainy' (similar in meaning).
The initial letter of 'get' is 'g'.
'g'+'rainy'='GRAINY'
(Other definitions for grainy that I've seen before include "Coarse" , "Old still can be this" , "gravelly" , "(Of photo) having low resolution" , "not clear" .)