Reserve shown by old company head (7)
I believe the answer is:
iciness
'reserve' is the definition.
(thesaurus)
'shown by old company head' is the wordplay.
'shown by' is a charade indicator (letters next to each other).
'old company' becomes 'ici' (former company Imperial Chemical Industries**).
'head' becomes 'ness' (ness is a headland).
'ici' put next to 'ness' is 'ICINESS'.
(Other definitions for iciness that I've seen before include "Such weather" , "unfriendly manner" , "Unapproachability" , "Hostility, unfriendliness" , "State of being very cold or distant" .)