Crane's action when flying across the Atlantic? (12)
I believe the answer is:
transoceanic
'across the atlantic?' is the definition.
(transoceanic means across an ocean)
'crane's action when flying' is the wordplay.
'when flying' is an anagram indicator (letters fly around).
'cranes'+'action'='cranesaction'
'cranesaction' is an anagram of 'TRANSOCEANIC'.
(Other definitions for transoceanic that I've seen before include "across the water" , "across the Pacific, say?" , "Crossing, eg, the Atlantic" .)