In action, perhaps, an about-turn calls for care (7)
I believe the answer is:
caution
'care' is the definition.
('caution' can be a synonym of 'care')
'in action perhaps an about-turn' is the wordplay.
'in' means one lot of letters goes inside another.
'perhaps' indicates an anagram.
'an about turn' becomes 'u' (a 'U-turn' is a kind of turn. I am not sure about the 'about' bit.**).
'action' anagrammed gives 'cation'.
'cation' enclosing 'u' is 'CAUTION'.
'calls for' acts as a link.
Can you help me to learn more?
(Other definitions for caution that I've seen before include "Formal warning for a minor offence" , "Admonish - warning" , "Care, prudence" , "Prudent wariness" , "Attention to possible danger" .)