Ask time rudely, making blunder (7)
I believe the answer is:
mistake
'blunder' is the definition.
(both can mean an error)
'ask time rudely' is the wordplay.
'rudely' indicates anagramming the letters (rude can mean rough or unrefined).
'ask'+'time'='asktime'
'asktime' is an anagram of 'MISTAKE'.
'making' acts as a link.
(Other definitions for mistake that I've seen before include "Error" , "Oversight" , "Wrong action or judgment" , "Fault" , "16 down" .)