From The Enigma
NPL Magazine
December, 2015
LEXMAN

The two key words in this flat (ONE and TWO) differ by only a single letter. Each word has six letters, and the first five letters are the same.

She spent the day ONE in a TWO ,
No sunscreen - when the day was through
Her face was red,
Her back and legs and shoulders too.

HINT:
The last letters of the two words are G and I, respectively

Answer:

BIKING - BIKINI