A fellow with iron, cold man, being influenced (8)
I believe the answer is:
affected
'being influenced' is the definition.
(I've seen this before)
'a fellow with iron cold man' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'with' means one lot of letters go next to another.
'iron' becomes 'Fe' (Fe is the chemical symbol for iron).
'cold' becomes 'c' (eg on taps).
'man' becomes 'ted' (Ted is a man's name).
'a'+'f'+'fe'+'c'+'ted'='AFFECTED'
(Other definitions for affected that I've seen before include "Impacted on" , "Made a difference to" , "Not natural" , "mincing?" , "Artificial in manner, phoney" .)