Keep company with awfully tense friar (10)
I believe the answer is:
fraternise
'keep company with' is the definition.
('keep company with'->'fraternize' is in my internal thesaurus and 'ize'->'ise')
'awfully tense friar' is the wordplay.
'awfully' indicates an anagram.
'tense'+'friar'='tensefriar'
'tensefriar' is an anagram of 'FRATERNISE'.
(Other definitions for fraternise that I've seen before include "Meet socially" , "Trains free (anag.)" , "Consort" , "Be friendly with" , "Associate with" .)