No longer apprehensive of grammatical term (4,5)
I believe the answer is:
past tense
'grammatical term' is the definition.
'no longer apprehensive' is the wordplay.
'no longer' becomes 'past'.
'apprehensive' becomes 'tense'.
'past'+'tense'='PAST TENSE'
'of' acts as a link.
(Other definitions for past tense that I've seen before include "What could be perfect in a lesson of French" , "It expresses something that has happened" , "Grammatical verb form" , "history?" , "Form of verb showing that the action has already happened" .)