One four-letter word in place of another? (4)
I believe the answer is:
dash
'word in place of another?' is the definition.
I can't judge whether this definition defines the answer.
'one four-letter' is the wordplay.
'one four' becomes 'das' (I am not sure about this - if you are sure you should believe this answer much more).
'letter' becomes 'h'.
'das'+'h'='DASH'
Can you help me to learn more?
(Other definitions for dash that I've seen before include "Confound - verve" , "Run quickly - little taste - hyphen" , "Destroy (hopes); run" , "Sudden quick run" , "quite mild oath" .)