Fear that calls for a cool head after a nasty pain (5)
I believe the answer is:
panic
'fear that' is the definition.
'panic' can be an answer for 'fear' (panic is a kind of fear). I'm not certain of the rest of the definition.
'a cool head after a nasty pain' is the wordplay.
'head' indicates taking the first letters.
'after' says to put letters next to each other.
'a nasty' indicates an anagram (a nasty or wrong spelling).
The initial letter of 'cool' is 'c'.
'pain' is an anagram of 'pani'.
'c' put after 'pani' is 'PANIC'.
'calls for' is the link.
Can you help me to learn more?
(Other definitions for panic that I've seen before include "Agitation" , "Sudden alarm" , "Lose one's cool" , "Sudden overpowering fright" , "Sudden infectious terror" .)