A head linked to old US space programme (6)
I believe the answer is:
apollo
'us space programme' is the definition.
I can't judge whether this definition defines the answer.
'a head linked to old' is the wordplay.
'head' becomes 'poll' (poll is a now rare word for head or scalp).
'linked to' is a charade indicator (letters next to each other).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'a'+'poll'+'o'='APOLLO'
Can you help me to learn more?
(Other definitions for apollo that I've seen before include "Greek sun god and leader of the Muses" , "handsome youth" , "US spacecraft" , "US space flight programme, 1961-72" , "Greek god; large European butterfly" .)