Some bloke, 50, encountered by the front of Sainsbury's, delivering hats (7)
I believe the answer is:
helmets
'hats' is the definition.
(helmet is a kind of hat)
'some bloke 50 encountered by the front of sainsbury's' is the wordplay.
'some bloke' becomes 'he' ('he' refers to a man).
'50' becomes 'l' (Roman numeral).
'encountered' becomes 'met' ('meet' can be a synonym of 'encounter').
'by' is a charade indicator (letters next to each other).
'the front of' says to take the initial letters (the letter at the front of the word).
The initial letter of 'sainsbury' is 's'.
'he'+'l'+'met'+'s'='HELMETS'
'delivering' acts as a link.
(Other definitions for helmets that I've seen before include "Protective head coverings" , "Protective head-gear" , "Protective head plates" .)