Pleasant company in a glen when rambling (9)
I believe the answer is:
congenial
'pleasant' is the definition.
(I've seen this in another clue)
'company in a glen when rambling' is the wordplay.
'company' becomes 'co' (abbreviation).
'when rambling' indicates anagramming the letters (I've seen this in other clues).
'in'+'a'+'glen'='inaglen'
'inaglen' is an anagram of 'ngenial'.
'co'+'ngenial'='CONGENIAL'
(Other definitions for congenial that I've seen before include "relaxing" , "Having similar interests" , "Harmonious and friendly" , "Pleasant and agreeable" , "Suited to one's taste" .)