Meat suppliers receiving telegram about headgear (8)

'meat suppliers' is the definition.
Although both the answer and definition are plural nouns, I can't see how one could define the other.

'receiving telegram about headgear' is the wordplay.
'receiving' indicates putting letters inside.
'telegram' becomes 'wire' (synonyms).
'about' shows that the letters should be reversed in order.
'headgear' becomes 'pigs' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'wire' backwards is 'eriw'.
'eriw' inserted into 'pigs' is 'PERIWIGS'.

Can you help me to learn more?