Close, so ran back to have an argument (6)
I believe the answer is:
narrow
'close' is the definition.
(similar in meaning)
'ran back to have an argument' is the wordplay.
'back' says the letters should be written in reverse.
'to have' says to put letters next to each other.
'an argument' becomes 'row' (to row is to argue).
'ran' back-to-front is 'nar'.
'nar'+'row'='NARROW'
'so' acts as a link.
(Other definitions for narrow that I've seen before include "Strait, tight" , "Strait, not wide" , "Strait or thin" , "Limited in scope; not wide" , "Having little breadth" .)