Cravat right for rank (4)
I believe the answer is:
tier
'for rank' is the definition.
(tier is a kind of rank)
'cravat right' is the wordplay.
'cravat' becomes 'tie' (I've seen this in another clue).
'right' becomes 'r' (common abbreviation).
'tie'+'r'='TIER'
(Other definitions for tier that I've seen before include "Level within hierarchy" , "He might do sailor's knots" , "Storey" , "One who secures" , "Row - one forming a knot" .)