Danger of salesman returning: I left (5)
I believe the answer is:
peril
'danger' is the definition.
(peril is a kind of danger)
'salesman returning i left' is the wordplay.
'salesman' becomes 'rep' (sales representative).
'returning' is a reversal indicator.
'left' becomes 'L' (common abbreviation).
'rep' reversed gives 'per'.
'per'+'i'+'l'='PERIL'
'of' is the link.
(Other definitions for peril that I've seen before include "Immediate danger" , "Hazardous situation" , "Danger, jeopardy" , "Source of danger" , "Great danger" .)