Fell in with German finding a berth (7)
I believe the answer is:
mooring
'a berth' is the definition.
('mooring' can be a synonym of 'berth')
'fell in with german' is the wordplay.
'fell' becomes 'moor' (I've seen this before).
'with' means one lot of letters go next to another.
'german' becomes 'g' (abbreviation).
'moor'+'in'+'g'='MOORING'
'finding' acts as a link.
(Other definitions for mooring that I've seen before include "Place to tie up boat" , "Place to leave a boat" , "Place to keep a boat" , "where boat is secured" , "Making fast" .)