Naval architect? (4)
I believe the answer is:
wren
'architect' is the definition.
(Christopher Wren, 17th-century architect)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for wren that I've seen before include "Tiny brown songbird with short erect tail" , "Type of small bird" , "Navy girl" , "Architect of St Paul's Cathedral" , "Small active brown northern hemisphere bird" .)