Familiar with international being dropped off outside ground (4,2)
I believe the answer is:
used to
'familiar with' is the definition.
(I've seen this in another clue)
'international being dropped off outside ground' is the wordplay.
'international' becomes 'i' (abbreviation eg in IMF).
'being dropped off' indicates named letters should be taken away.
'ground' indicates an anagram ('grind' the letters into a new form).
'outside' with 'i' taken out is 'outsde'.
'outsde' is an anagram of 'USED TO'.
(Other definitions for used to that I've seen before include "Was in the habit" , "Familiar with" , "Not unfamiliar with" , "Did at times in the past" , "Accustomed or inured" .)