Asked for decimal approximation (7)
I believe the answer is:
claimed
'asked' is the definition.
(claiming is a kind of asking)
'decimal approximation' is the wordplay.
'decimal' can be anagrammed to 'CLAIMED'.
Though, I am not sure how the anagram is indicated.
'for' is the link.
Can you help me to learn more?
(Other definitions for claimed that I've seen before include "Called for" , "Asserted, contended" , "Declared" , "Alleged" , "Asserted right to or interest in" .)