Health resort given mass of processed meat (4)
I believe the answer is:
spam
'processed meat' is the definition.
(I've seen this before)
'health resort given mass' is the wordplay.
'health resort' becomes 'spa' (spa can mean a health resort).
'given' means one lot of letters go next to another.
'mass' becomes 'm' (symbol used in Physics e.g. f=ma).
'spa'+'m'='SPAM'
'of' is the link.
(Other definitions for spam that I've seen before include "Spiced ham" , "Computer junk mail" , "Tinned meat - unwanted email" , "Unwelcome approach" , "unwanted delivery" .)