LAST_ENTRY  SET $00 ; initially set to 0/null

;; probably getting the syntax wrong

defword    MACRO
CUR_ENTRY SET @    ; stash address of current entry
    dw LAST_ENTRY  ; lay down previous address
    db \1          ; lay down argument
LAST_ENTRY SET CUR_ENTRY  ; update prev address
    ENDM

;; if code starts at address $100
defword 'test'
defword 'test2'
defword 'test3'

;; should result in
    dw $00
    db 'test'

    dw $106   ; pointer to 'test' entry
    db 'test2'

    dw $10D   ; pointer to 'test2' entry
    db 'test3'