While coming back, I crossed over remote expedition (6)
I believe the answer is:
safari
'remote expedition' is the definition.
'safari' can be an answer for 'expedition' (safari is a kind of expedition). I'm not sure about the 'remote' bit.
'while coming back i crossed over' is the wordplay.
'while' becomes 'as'.
'coming back' shows that the letters should be reversed in order.
'crossed' becomes 'far' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'over' means one lot of letters go next to another.
'as' in reverse letter order is 'sa'.
'i' after 'far' is 'fari'.
'sa'+'fari'='SAFARI'
Can you help me to learn more?
(Other definitions for safari that I've seen before include "African hunting expeiditon" , "African wildlife trip" , "Overland journey to look for wild animals" , "Big game trip" , "Trip to see wild animals" .)