Pity about cutting new individual transmitter (7)
I believe the answer is:
neurone
'transmitter' is the definition.
(neurones transmit nerve impulses)
'pity about cutting new individual' is the wordplay.
'pity' becomes 'rue' (I've seen this in other clues).
'about' is a reversal indicator.
'cutting' is an insertion indicator (some letters cut their way into a word).
'new individual' becomes 'none' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'rue' in reverse letter order is 'eur'.
'eur' placed into 'none' is 'NEURONE'.
(Other definitions for neurone that I've seen before include "Nerve centre" , "Cell that conducts nerve impulses" , "cell often seen with motor" .)