The architect Hans became (4)
I believe the answer is:
nash
'the architect' is the definition.
(I've seen this before)
'hans became' is the wordplay.
'became' is an anagram indicator (I've seen 'become' mean this).
'hans' with letters rearranged gives 'NASH'.
(Other definitions for nash that I've seen before include "new wood" , "Famed English architect" , "John -, Eng. architect" , "Ogden --, author" , "Uncontrollable emotion" .)