Danger left one representative receding (5)
I believe the answer is:
peril
'danger' is the definition.
('peril' can be a synonym of 'danger')
'left one representative receding' is the wordplay.
'left one' becomes 'li' (left abbreviation plus 1).
'representative' becomes 'rep' (rep is a kind of representative).
'receding' is a reversal indicator.
'li'+'rep'='lirep'
'lirep' back-to-front is 'PERIL'.
(Other definitions for peril that I've seen before include "risk" , "Danger of serious kind" , "Exposure to harm" , "Immediate danger" , "Quest" .)