Man starts to call headquarters at Poole (4)
I believe the answer is:
chap
'man' is the definition.
(term for a man)
'starts to call headquarters at poole' is the wordplay.
'starts to' indicates taking the first letters.
The first letters of 'call headquarters at poole' is 'CHAP'.
(Other definitions for chap that I've seen before include "Sore; cheek; man" , "Become raw from cold - fellow" , "Fellow < makes > crack" , "Raw, cracked patch on skin" , "Fish" .)